Summary

Customize for own drill bit diameter.

See new version https://www.thingiverse.com/thing:6827873

Use screw for fixing stopper.

For high speed drilling, use two screws to eliminate imbalance.

Created at theOpenScad and can be converted to Customizer, but use external library:

threads.scad - https://github.com/verhas/OpenScad/blob/main/threads.scad

After downloading, you can use the customizer.
However, remember about the need a threads library.